Skin trimmer attachment for air drill motors



April 1960 D. KENNEDY ETAL 2,933,021

SKIN TRIMMER ATTACHMENT FOR AIR DRILL MOTORS Filed Dec. 21, 1955 JESSE L.TURNER IRA D- KENNEDY INVENTOR5 ATTORN EY Patented Apr. 19, 1960 SKIN TRIMMER ATTACHMENT FOR AIR DRILL MOTORS Application December 21, 1955, Serial No. 554,539

Claims. (Cl. 90-12 This invention is generally concerned with the art of cutting sheet material, and relates more particularly to an apparatus for abutting one sheet to another.

A problem peculiar to the aircraft industry is the accurate mating of skin panels to wing understructures. In this regard it can be appreciated that, when one panel has been riveted in place, in order to produce a butt joint with the next adjacent panel, one of the panels must be trimmed so that a close fit is realized.

Accordingly, one important object of the instant invention is to assure that the various skin panels will accurately mate with each other, thereby presenting a smooth flush surface that will Offer a minimum of wind resistance when the apparatus forming the subject matter of the invention is used in conjunction with the construction of planes and the like. Of course, while the invention will find special utility when used as above described, it lends itself readily to other sheet fabrication tasks, should the job require closely fitted butt joints.

Another object is to permit the production of an interfitting butt joint at the construction site, rather than having to pre-form such joints at a central location.

Another object of the invention is to provide a skin trimmer attachment that can be employed in association with conventional drilling equipment, such as portable air or electric drill motors, thereby permitting the invention to be practiced without need for investing in extensive and expensive equipment.

A further object is to provide apparatus for butt jointing sheets of material in a minimum of time and with relatively inexperienced personnel.

Yet another object resides in the trimming of only one edge of two adjacent panels. Y I

A still further object of the invention is to permit control of the space between the adjacent ends of two sheets, it being possible to adjust the tool so as to make a tight butt joint or to leave a slight space between the edges of the panels after trimming.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application which will be indicated in the appended claims.

In the drawing:

Figure 1 is a side elevational view of the skin trimmer attachment together with a drill motor mounted thereon;

Figure 2 is a front view of the apparatus depicted in Figure l, the view additionally showing a pair of panels to be butt jointed with each other;

Figure 3 is a view similar to Figure 1 but fragmentarily picturing the other side of the apparatus constituting Figure 1, and 7 Figure 4 -is a perspective view of the apparatus in actual use.

Referring in detail to the drawing, there is shown in phantom outline portions of a pair of sheet metal panels 16 and 12. The panel 10 has been completely riveted to its underlying supporting structure, several rivets 14 being visible near one marginal edge 16. On the other hand, the other panel 12 has been riveted at locations 18 which are spaced from its marginal edge 20. Owing to the above-mentioned spacing and the inherent resiliency or flexibility of the relatively thin panel 12, it will be appreciated that the free edge 20 may be readily flexed upwardly with respect to the panel 10, as may best be seenin Figure 2. For a purpose presently to be described more fully, his to be noted that there is an overlapping relationship existing between the marginal edges 16 and 20, such a relationship having been provided just prior to the riveting operation.

meral 22. The attachment 22 comprises a guide shoe element 24 having a forward end or toe 26 which has an inclined upper surface which aids introduction of the forward end of the shoe between the overlapped margins of the panels 10 and 12, the sharp end of the toe 26 serving to wedge the panel 12 upwardly and thus separate the two panels to an extent governed by the vertical thickness of the shoe element.

The lower surface of the shoe 24 carries an integral depending flange 28 along one side 30 thereof. The distance that the flange 28 extends downwardly from the relieved surface 32' hould be no greater than the thickness of the guiding panel 10. In this way the surface 32 is permitted to ride on the upper surface of the panel 10, serving to support the shoe 24 and its superstructure yet to be described. The flange 28, on the other hand,

is intended to bear against the edge 16 and functions as a guide for the entire attachment 22.

Welded or otherwise rigidly secured to the top of the shoe 24 is an elongated web 34 which rigidly supports a somewhat longer overhanging horizontal plate 36, to which is rigidly welded an upright standard 38. Stand ard 38 is fitted with grip pads 40' and serves both as a handle and as a motor support.

To the upper end of the standard 38 is attached a motor clamping band 42, a screw 44 serving as the means of securement. The band 42 embraces a motor housing 46, depicted in phantom outline so as to emphasize that it need not form an integral part of the attachment. Resort to a. conventional air 'or electric drill motor for the driving device will serve to provide an inexpensive source of motive power and is recommended. Some means of anchoring the lower end of the housing 46 is desirable in order to obviate any shifting thereof during a cutting operation. In the illustrated embodiment the housings lower end is rendered immobile by means of a plate or strip 48, afiixed to the motor housing, as by screws not visible in the drawing. Screws 50 and 52 extend through apertures in the opposite ends of the strip 48 into tapped holes in the plate 36. In this way the motor housing is held fast at both its upper and lower ends.

A drill bit 54 is rotated by the motor contained in the housing 46, this bit projecting downwardly through sufficiently large apertures in both the strip 48 and the plate 36. As can be readily discerned from Figure 3, the lower'end of the bit 54 extends into a recess 56 formed in the shoe 24 but terminates at an elevation above the lower surface 32 of the shoe. The cutting bit 54 should be slightly larger in diameter than the width of the flange 34, as clearly shown in Fig. 2.

Aiding in the steadying of the attachment 22 during use thereof is a pair of laterally extending rollers 58 and 60 free to rotate on fixed spindles 62 threaded into a tapped holes in that side of the shoe opposite the flange 28. 'From Figure 2 it can be seen that the lower periphery of these rollers 58, 60 is such that a coplanar relationship is established with the surface 32. Thus the rollers 58, do likewise ride on the upper surface of the panel '10 during the trimming operation.

In operation, the panels and 12 are anchored in an overlapping relation by properly choosing the sites for the rivets 14 and 18. It will be remembered that the rivets 18 are spaced somewhat from the edge 20 of the panel 12, the exact distance depending primarily upon the flexibility of the panel being trimmed.

When the above overlapping condition has been obtained, then the trimming operation can 'be initiated. Accordingly, the toe 26 of the shoe 24 is inserted between the overlapped portions of the panels .10 and 12, thereby urging or flexing the panel 12 upwardly in the area bordering the edge 20. The flange '28 is positioned against-the guiding edge 16 of theguide panel 10, which acts asa guidingmedium or pattern throughout the ensuing trimming in which material is removed from the edge 20 .of panel 12.

As the attachment 22 is advanced, the bit 54 moves into cutting contact with the panel 12 and continued movement of the attachment .results in the cutting of a slot 64, as evidenced in Figure 4, having a width equal of course to the diameter of the bit 54. This trimming action leaves a new edge 66 identical in profile to the edge 16 of panel 10. The flange 34- follows the bit in an aligned tandem fashion in the slot 64- until the marginal strip 68 (Fig. 4) has been severed from the panel 12.

As stated earlier herein, it is within the purview of the inventionto vary the spacing between the edge 16 and the new edge 66, just formed. It can be observed that shifting of the bit 54 to the left as viewed in Figure 2 will have the effect of narrowing the gap or spacing which willbe produced by the described trimming operation, whereas displacement to the right will, ofscour.se, increase the gap. One of the simplest ways of achieving such bit adjustment is to make the apertures in the strip 48, through which the shanks of the screws 50 and 52 extend, oversized, thereby affording clearance for shifting the entire motor housing 44, together with its bit, relative to the shoe 24 and its depending flange 28, when these screws have been loosened sufiiciently.

Since the edge '16 serves as a guide, any irregular angularity thereof is automatically transferred to the bit 54 via the attachment 22, thereby imparting the same complemental degree of irregularity to the ultimate edge 66. By disposing the bit 54 so that its right side is in vertical alignment with the edge 16 a tight matingfit will be produced. Thus it can be seen that two adjacent ends of a pair of sheets or panels can be juxtaposed in a'hutt relationship, either contiguously or proximately, utilizing the apparatus constituting my invention.

As many changes could be made in the above construction and many apparently widely diiferent embodiments of the invention could be made without departing from the scope thereof, it is intended that allmatter contained in ,the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed:

1. ,The improvement in 'a sheet cutting machine for forming a butt joint between first and second fixed position metal sheets meeting in overlapping margins, comprising: a guide shoe having a first guiding means, said first sheet having an edge overlapped by said second sheet and said first guiding means abutting and being movable along said edge whereby said edge acts as a guide template to cut a complementally contoured edge on the margin of said second sheet, said guide shoe having second guiding means disposed at right angles to said first guiding means and engaging the top marginal face of said first sheet and being movable along said marginal face whereby said second guiding means acts to position the guide shoe relative to said marginal face of said first sheet, a motor secured to said guide shoe and cutter means supported and powered by said motor disposed above said first guiding means and positioned to engage said margin of said second sheet and to out said complementally contoured edge on said second sheet as said first guiding means of said shoe is moved along said edge of said first sheet, said cutter means being disposed rela tive to said first guiding means so that said complementally contoured edge will lie closely adjacent to said edge of said first sheet to form said butt joint, said motor being secured to said guide shoe by means including a web having less thickness than said cutter means whereby said web may pass through said margin of said second sheet .in the slot cut therein by said cutter means as it forms said complementally contoured edge.

2. The improvement in a sheet cutting machine f r forming a butt joint between first and second sheets meeting in overlapping margins, comprising: a guide shoe to be disposed between said sheets, said guide shoe having a first guiding means formed by a depending flange to be abutted to and to be moved along an edge of said first sheet overlapped by said second sheet whereby said edge acts as a guide template to cut a complementally contoured edge on the margin of said second sheet, said guide shoe having second guiding means including roller means projecting laterally from said shoe, said second guiding means being disposed at right angles to said first guiding means to engage the top marginal face of said first sheet and to be moved therealong whereby said second guiding means acts 'to' position the guide shoe relative to said top marginal face of said first sheet, a motor secured to said guide shoe and rotary bit type cutter meanssupported andpowered by said motor, said guide .shoe having a recess on its edge receiving said cutter means-in position above said first guiding means whereby said cutter means will be positioned to engage said margin of said second sheet and to cut said complementally contoured edge'on said second sheet when said first guiding means of said' shoe is moved along said edge of said first sheet, said cutter means being disposed relative to said first guiding means so that when said cutter means cuts said complementally contoured edge it will lie closely adjacent to said edge of said first sheet to form said butt joint, said motor being secured to said .guide shoe by securing means including a web having less. thickness than said cutter means whereby said web may pass through said margin of said second sheet in the slot cut therein by said cutter means as it forms said complementally contoured edge.

3. The improvement in a sheet cutting machine for forming a butt joint between first and second sheets meeting in overlapping margins, comprising: a guide shoe having a first guiding means, said first sheet having an edge overlapped by said second sheet and said first guiding means abutting and being movable along said edge whereby said edge acts as a guide template to cut a complementally contoured edge on the margin of said second sheet, said guide shoe having second guiding means disposed at right angles to said first guiding means and engaging the top marginal face of said first sheet and being movable along said marginal face whereby said second guiding means acts to position the guide shoe relative to said marginal face of said first sheet, a mo tor secured to said guide shoe and cutter means supported and powered by said motor disposed above said first guiding means and positioned to engage said margin of said second sheet and to cut said complementally contoured edge on said second sheet as said first guiding means of said shoe is moved along said edge of said first sheet, said cutter means being disposed relative to said first guiding means so that said complementally contoured edge out therebywill lie closely adjacent to said edge of said first sheet to form said butt joint.

4. The improvement in a sheet cutting machine for forming a butt joint between first and second sheets meeting in overlapping margins, comprising: a guide shoe having a guiding surface, said first sheet having an edge overlapped by said second sheet and said guiding surface abutting and being slidable along said edge whereby said edge acts as a guide template to cut a com plementally contoured edge on the margin of said second sheet, a motor secured to said guide shoe and cutter means supported and powered by said motor disposed above said guiding surface and positioned to engage said margin of said second sheet and to out said complementally contoured edge on said second sheet as said guiding surface of said shoe is moved along said edge of said first sheet, said cutter means being disposed relative to said guiding surface so that said complementally contoured edge cut thereby will lie closely adjacent to said edge of said first sheet to form said butt joint, said motor being secured to said guide shoe by means including a web having less thickness than said cutter means and disposed to pass through said margin of said second sheet in the slot cut therein by said cutter means as it forms said complementally contoured edge.

5. The improvement in a sheet cuttingmachine for forminga butt joint between first and second sheets meeting in overlapping margins, comprising: a guide shoe between said sheets resting on the mar-gin of said first 6 sheet and supporting the marginal portion of said second sheet being cut, said guide shoe having a depending guiding surface, said first sheet having an edge overlapped by said second sheet and said guiding surface abutting.

and being movable along said edge whereby said edge acts as a guide template to cut a complementally contoured edge on the margin of said second sheet, cutter means supported by said guide shoe above said depending guiding surface and positioned to engage said margin of, said second sheet and to out said complementally contoured edge on said second sheet as said guiding surface of said shoe is moved along said edge of said first sheet, said cutter means being disposed relative to said guiding surface so that said complementally contoured edge will lie closely adjacent to said edge of said first sheet to form said butt joint.

References Cited in the file of this patent UNITED STATES PATENTS 1,275,899 Freydberg Aug. 13, 1918 1,589,156 Hartman June 15, 1926 1,798,250 Galvin Mar. 31, 1931 1,977,194 Malkovsky- Oct. 16, 1934 2,140,120 Tomarin Dec. 13, 1938 2,246,761 Saliba et a1 June 24, 1941 2,483,092 Hanke Sept. 27, 1949 2,599,415 Russell June 3, 1952. 2,696,857 Groehn et a1. Dec. 14, 1954 2,723,598 Mann Nov. 15, 1955 2,747,271 Raehrs May 29, 1956 

